Incidentally, she also explained that 毛小孩 (mao2 xiao3 hai2) is a reference to pets [hairy small children] that are doted on and that to be 紅 (hong2) in this case is to be a celebrity or popular. Red is a color associated both with good luck and stands out conspicuously.

❶ A more completely accurate way of saying this would be to include the word for “to feel” 感覺 (gan3 jue2) right before the word that means “hot,” but, just like in English, sometimes words are left out for saying something quickly or for word play. With this included, the whole phrase would be:

怎麼知道你自己感覺熱的指數破表了

❷ In case you didn’t notice, I am using the description “mama” here to go along with people referring to their pets as children. But I will switch later on when I want to indicate a change in attitude.

❸ The two descriptions indicating extreme levels, 破表了 (po4 biao3 le.) “to break the scale” and 超過 (chao1 guo) “to surpass,” would not be used in the same sentence.

❹ I am most familiar with using 有 (you3) as “to have,” but one of its complimentary meanings is “there is.” Thus, 有多熱 (you3 duo1 re4) means “there is much heat” or “how hot it is.” Knowing this form: 有多 + adjective = how (fill in adjective) it is! can help to remember how to use it for other sentences.

❺ There are other ways to say this. There is the now commonly used 夯 (hang1), which also means “hot.” The more flowery description of 紅到 (hong2 dao4),literally means “red to arrive,” but is taken to mean “popular, eminent, specially favored to a point.” Add the 破表了 (po4 biao3 le.) and it means “hot to a point that breaks the meter or scale or whatever is being used to measure this.”

This type of wording can be used with anything in the form [adjective or noun + 到 (dao4) + result or evaluation]. Examples my tutor gave me:

他生氣到不想吃飯。 He is mad to the point he doesn’t feel like eating.

我高興到不能睡覺。 I am happy to the point that I can’t sleep!

我熱到只想喝水。 I am hot to the point I just want to drink water.

(You can look up characters you don’t recognize by hand writing them on the KTdict Chinese-English app, or ask in the comments and I can tell you)

❻ Other meanings for (da4) are “highly, greatly, very,” so in this sentence they give the meaning of “more and more highly heat tolerant.”